U.S. patent number 4,293,413 [Application Number 06/108,118] was granted by the patent office on 1981-10-06 for dialyzer blood circuit and bubble traps.
This patent grant is currently assigned to Baxter Travenol Laboratories, Inc.. Invention is credited to William J. Schnell.
United States Patent |
4,293,413 |
Schnell |
October 6, 1981 |
Dialyzer blood circuit and bubble traps
Abstract
A blood dialyzer system which comprises a membrane dialyzer
carried by dialysis solution delivery means and having blood and
dialysis solution inlets and outlets. The membrane dialyzer is
carried in a position whereby the blood inlet is vertically lower
than the blood outlet, and the dialysis solution outlet is
vertically lower than the dialysis solution inlet. Bubble trap
means are provided in direct communication with the blood outlet
and blood flow conduits, with the bubble trap means being
preferably attached to and carried by the membrane dialyzer. The
dialysis solution delivery means is adapted to permit intermittent
reversal of the normal flow of dialysis solution through the
membrane dialyzer to remove air bubbles trapped therein. Also,
improved designs of integral bubble traps carried by dialyzers are
shown.
Inventors: |
Schnell; William J. (Wheeling,
IL) |
Assignee: |
Baxter Travenol Laboratories,
Inc. (Deerfield, IL)
|
Family
ID: |
22320419 |
Appl.
No.: |
06/108,118 |
Filed: |
December 28, 1979 |
Current U.S.
Class: |
210/188;
210/321.78 |
Current CPC
Class: |
A61M
1/3627 (20130101); A61M 1/16 (20130101) |
Current International
Class: |
A61M
1/36 (20060101); A61M 1/16 (20060101); B01D
031/00 () |
Field of
Search: |
;165/158
;210/22,321B,188,425 ;55/52,190 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spear, Jr.; Frank A.
Attorney, Agent or Firm: Flattery; Paul C. Ellis;
Garrettson
Claims
That which is claimed is:
1. A blood dialyzer system which comprises a membrane dialyzer
carried by dialysis solution delivery means, said membrane dialyzer
defining a blood inlet and outlet communicating with blood flow
conduits, and also defining a dialysis solution inlet and outlet
communicating through solution flow conduit means with said
dialysis solution delivery means, said membrane dialyzer being
carried in a position whereby said blood inlet is vertically lower
than said blood outlet, and said dialysis solution outlet is
vertically lower than said dialysis solution inlet, and bubble trap
means in direct communication with said blood outlet and blood flow
conduits, said bubble trap means being attached to and carried by
said membrane dialyzer, said dialysis solution delivery means being
adapted to intermittently reverse the normal flow of dialysis
solution through said membrane dialyzer to remove air bubbles
trapped in said membrane dialyzer.
2. The blood dialyzer system of claim 1 in which said membrane
dialyzer is of the countercurrent flow type.
3. The blood dialyzer system of claim 2 in which the axis of the
main dialysate flow path in the membrane dialyzer occupies an angle
of 20.degree. to 60.degree. with the vertical, with said dialysis
solution inlet and outlet pointing upwardly from the
horizontal.
4. The blood dialyzer system of claim 3 in which said bubble trap
means comprises a distinct, enlarged chamber area at an upper
portion thereof connected by a step wall to a lower portion thereof
which is not transversely enlarged, and a conduit for receiving
blood from said blood outlet spaced from the bottom of said chamber
and communicating directly with said enlarged upper chamber portion
in an upwardly-pointing direction through said step wall, an outlet
positioned adjacent the end of said lower portion remote from said
enlarged, upper portion of said chamber, and vent means for gases
being positioned at the upper end of said receiving chamber.
5. The blood dialyzer system of claim 4 in which blood filter means
is positioned in the lower portion of said chamber.
6. The blood dialyzer system of claim 2 in which said bubble trap
means comprises a hollow housing member in the shape of a truncated
cone having a wide end and a narrow end, sealed to said dialyzer at
said wide end with said communicating blood outlet positioned
centrally therein, outlet port means in the wall of said housing
member, upstanding baffle means positioned longitudinally within
said hollow housing member and positioned in front of said outlet
port means but spaced therefrom, to prevent the direct flow of
blood from said outlet and to the outlet port means, and means for
the aseptic removal of collected bubbles positioned adjacent the
narrow end of said hollow housing member.
7. The blood dialyzer system of claim 6 in which the outlet port
means is positioned in the half of the housing member wall which is
adjacent to said wide end.
Description
BACKGROUND OF THE INVENTION
In the typical commercial dialyzer arrangement, particularly in the
case of hollow fiber-type dialyzers positioned in a tubular
housing, the dialysis solution inlet is positioned vertically lower
than the dialysis solution outlet of the dialyzer. Correspondingly,
in the case of hollow fiber dialyzers, this requires, for the
optimum counterflow arrangement, that the blood inlet be positioned
vertically higher than the blood outlet.
The reason for the above arrangement is that the bubbles which may
pass into the dialyzer through the dialysis solution flow path can
be swept out of the dialyzer in a much more effective manner if the
dialysis solution outlet is positioned vertically above the inlet.
In the opposite circumstance, bubbles may collect in the dialysis
solution flow path, which interferes with the dialysis efficiency
of the device.
In this conventional circumstance, where the blood flows
downwardly, typical dialysis arrangements have called for an
upstream bubble trap in the blood flow line, to keep air out of the
blood flow path of the dialyzer, to avoid air blocking of the
membrane flow channels, which can take place because of the natural
buoyancy of air, which tends to try to rise against the
downwardly-flowing current of the blood.
Also, a downstream bubble trap must be provided in the blood flow
circuit of the dialysis system for safety, since it is imperative
to avoid the infusion of air bubbles to the patient.
In accordance with this invention, an improved dialysis system is
provided which permits the elimination of one of the bubble traps
in the blood flow circuit, which of course results in a significant
cost savings in each dialysis procedure.
The invention of this application takes advantage of improved
dialysis delivery system techniques to permit the simplification of
the dialysis system resulting from a downward flow path of the
dialysis solution through the dialyzer.
Furthermore, the system of this invention may be simplified for the
user by providing a bubble trap which is integral with the dialyzer
unit, carried at the outlet of the blood flow path from the
dialyzer, for greater ease of setup by the user.
DESCRIPTION OF THE INVENTION
In accordance with this invention, a blood dialyzer, or any other
type of membrane diffusion device, is provided which comprises a
membrane dialyzer carried by dialysis solution delivery means. The
membrane dialyzer defines a blood inlet and outlet communicating
with a blood flow conduit, and also defines a dialysis solution
inlet and outlet communicating through solution flow conduit means
with the dialysis solution delivery means.
The membrane dialyzer is carried in a position whereby the blood
inlet is vertically lower than the blood outlet, and the dialysis
solution outlet is vertically lower than the dialysis solution
inlet.
Bubble trap means may be provided in direct communication with the
blood outlet and flow conduit, with the bubble trap means being
preferably attached to and carried by the membrane dialyzer.
The dialysis solution delivery means is adapted to intermittently,
as needed, reverse the normal flow of dialysis solution through the
membrane dialyzer, to remove air bubbles trapped in the membrane
dialyzer.
Preferably, this invention is used with membrane dialyzers which
are of the countercurrent flow type, for example, the commercially
available capillary fiber dialyzers such as the CF.RTM. dialyzers
sold by the Artificial Organs Division of Travenol Laboratories,
Inc., or plate type dialyzers.
Furthermore, the dialyzer of this invention may carry bubble trap
means in direct communication with the outlet of the blood flow
path, with the bubble trap means comprising a hollow housing member
in the shape of a truncated cone having a wide end and a narrow
end, sealed to the dialyzer at the wide end with the communicating
blood outlet end being positioned centrally therein. Outlet port
means may be provided in the wall of the bubble trap housing and
preferably positioned in the half of the housing wall which is
adjacent to the wide end, and most preferably closely adjacent to
the wide end.
Upstanding baffle means may be positioned longitudinally within the
hollow housing of the bubble trap, and positioned in front of the
outlet port means, but spaced therefrom, to prevent the direct flow
of blood from the outlet end of the blood flow path of the dialyzer
to the outlet port means. Means may also be provided for the
aseptic removal of collected bubbles positioned adjacent to the
narrow end of the hollow housing member. This means typically may
be a needle-piercable injection site.
In the drawings, FIG. 1 is an elevational view of a blood dialyzer
system in which a membrane dialyzer is shown to be attached to a
dialysis solution delivery means or machine.
FIG. 2 is a schematic diagram showing one mode of operation of a
flow reversal system for the dialysis solution delivery means shown
in this invention.
FIG. 3 is an elevational view of an alternate embodiment of the
membrane dialyzer, suitable for mounting on the dialysis delivery
means, and carrying another design of bubble trap.
Referring to FIGS. 1 and 2, a blood dialyzer system is provided
which comprises a membrane dialyzer 10 which is specifically shown
to be a conventional capillary fiber dialyzer similar to the
CF.RTM. dialyzer sold by the Artificial Organs Division of Travenol
Laboratories, Inc., attached to the housing 12 of a dialysis
solution delivery system 14 by conventional means, for example, a
resilient C-clamp 16 proportioned to allow the snap-fit of housing
18 of membrane dialyzer 10.
As shown, membrane dialyzer 10 defines a blood inlet 20 and a blood
outlet 22 communicating with blood flow conduit 24, 26.
Membrane dialyzer 10 also defines a dialysis solution inlet 28 and
outlet 30, with dialysis solution inlet 28 receiving dialysis
solution through line 32 from a solution outlet 34 in the dialysis
solution delivery means 14. The dialysis solution may be mixed from
concentrate, brought to the proper temperature, and debubbled by
the dialysis solution delivery system 14.
As can be seen from FIG. 1, membrane dialyzer 10 is carried in a
position whereby blood inlet 20 is vertically lower than blood
outlet 22. Correspondingly, the dialysis solution outlet 30 is
vertically lower than the dialysis solution inlet. Accordingly, any
bubbles which are present in the blood entering dialyzer 10 through
inlet 20 will tend not to be trapped but to pass upwardly out of
port 22. On the other hand, any bubbles which enter the dialysis
solution compartment of dialyzer 10 through inlet 28 may have a
tendency to be trapped within the dialyzer, since the flow of
dialysis solution is downward.
Because of the upward flow of the blood to the dialyzer, it no
longer is necessary to have a bubble trap positioned upstream of
dialyzer 10 in communication with blood flow conduit 24, which
results in a clear cost saving with respect to the disposable
equipment used herein, i.e., the dialyzer 10 and its blood flow
circuitry.
Membrane dialyzer 10 carries a bubble trap 36 preferably attached
to the membrane dialyzer, as shown. Conduit 26 may be permanently
sealed to outlet port 22. Bubble trap 36 comprises flexible conduit
26 for the inlet of blood, which may preferably be integral with a
flexible plastic bubble trap housing 38, which may be made out of
polyvinyl chloride plastic or the like.
Housing 38, as shown, defines a tubular, relatively enlarged upper
portion 40, which is closed by a cap 42, which contains a
conventional pressure monitor line 44 communicating with the
interior of the bubble trap, most of which is broken away for
purposes of clarity of disclosure. Also, a conventional needle
access port 46, normally sealed with a latex diaphragm or the like,
may be provided for sampling of the blood.
The lower portion 48 of flexible housing 38 defines a tubular
portion of reduced transverse dimension compared with the upper
portion 40, with the junction between upper portion 40 and lower
portion 48 being abruptly defined by a step wall portion 50.
In the lower end of lower portion 48, a conventional blood filter
52 may be provided which is sealed to the inner periphery of lower
portion 48, and a sealed blood outlet tube 54 to convey the
debubbled blood back to the arterial system of the patient.
The overall design of the bubble trap may be as disclosed in the
copending U.S. application Ser. No. 907,363, filed May 18, 1978, of
Marc Bellotti, et al. entitled "MEDICAL SET FOR A DIFFUSION
DEVICE".
As described below with respect to FIG. 2, any conventional
dialysis solution delivery system 14, capable of delivering
generally bubble-free dialysis solution to inlet 28 of dialyzer 10,
is provided. Even if some bubbles do form and are trapped in the
dialyzer, the dialysis solution delivery system 14 is preferably
capable of reverse dialysis solution flow by means shown in FIG. 2,
so that the bubbles may be removed from dialyzer 10 and sucked back
into the delivery system 14 through outlet 34, where the dialysis
solution and bubbles may be shunted to a drain. After this, the
flow is reversed again to its normal direction, and fresh,
bubble-free dialysis solution will once again pass through the
dialyzer between inlet 28 and outlet 30.
Blood passes, typically from the venous system of a patient, via
conduit 24, which may be part of a venous set, through inlet 20 and
outlet 22 of dialyzer 10, being dialyzed in conventional manner
against the counterflowing dialysis solution. Thereafter, blood
enters conduit 26, which may be part of an arterial set, with a
substantial upward flow component into bubble trap 36, where the
upward flow component impels bubbles in the blood upwardly above
the blood level in housing 38. Blood is withdrawn from the bottom
of lower portion 48, where the flow is relatively quiescent and
free of bubbles, so that the blood withdrawn through line 54 for
return to the arterial system of the patient is bubble-free.
As shown in FIG. 1, the longitudinal axis of the main flow path
through dialyzer 10 preferably occupies an angle of about
20.degree. to 60.degree. from the vertical so that the dialysis
solution inlet 28 and outlet 30 point upwardly to some extent. This
significantly facilitates the removal of air from dialyzer 10
during the priming procedure, and also in the event that air
bubbles must be removed from the dialysate compartment by reverse
operation of dialysis solution delivery system 14.
Conduit 26 may also define about a 20.degree. to 60.degree. angle
from the axis of lower portion 48.
As the result of the above improvement, a dialyzer unit is provided
having an integrally carried bubble trap communicating with the
blood outlet from the dialyzer. This provides substantial
convenience of assembly, with the entire arterial set of the
dialyzer system being optionally integral with the dialyzer 10 and
bubble trap 36. If desired, the venous set exemplified by conduit
24 may also be integrally attached to dialyzer 10 if desired. This
assures proper assembly of the apparatus, and places less burden
upon the user to provide sterile connection of the various set
components. At the same time, the venous set exemplified by conduit
24 can be greatly simplified and reduced in cost, since the need
for the venous set bubble trap is dispensed with.
Conduit 24 comprising a portion of the venous set may include other
conventional components of such a set, specifically, a T-connection
member 56 and a pressure monitor line 58, of which may communicate
with a conventional pressure monitoring apparatus.
Referring to FIG. 2, the flow reversing system 90 is shown, which
may be part of dialysis solution delivery system 14 and positioned
within or carried by housing 12. The remaining components of
dialysis solution delivery system 14 may be of any conventional
design. Various dialysis solution delivery systems are commercially
available at the present time.
Dialysis solution inlet line 92 leads from the conventional portion
of the dialysis solution delivery system 14, line 92 being provided
with a supply of degassed dialysis solution having a proper
concentration of solutes, and maintained at the proper
temperature.
Line 92 divided into a pair of branched lines 94, 96. Line 94 leads
to a three-way flow reversing solenoid valve 98, a type of which is
commercially available, for example, from Skinner Precision
Industries, Inc., of New Britain, Conn. Valve 98 also communicates
with dialysis solution inlet line 100 which, in turn, communicates
through aperture 34 to dialysis solution inlet 28 of dialyzer
10.
Valve 98 also communicates with drain line 102, with valve 98 being
mechanically operable to alternatively connect lines 94 and 100
while closing line 102 and lines 102 and 100 while closing line
94.
Dialysis solution passing out of outlet 30 enters flow line 104
which, in turn, communicates with three-way reversing solenoid
valve 106, which may be of similar design to valve 98. Valve 106 is
capable of alternatively providing communication between branch
line 96 and line 104 while blocking flow through connector line
108, which, in turn, communicates with drain line 102.
Alternatively, valve 106 can provide connection between lines 104
and 108 while blocking line 96.
Pressure monitors 110 may be connected to lines 100 and 104, and
blood leak detector 112 may be provided in drain line 102.
Accordingly, dialysis solution passing through line 92 may, in the
normal operating condition of valves 98, 106, pass through valve 98
into line 100, and from there through the dialyzer 10. Spent
dialysis solution exits from dialyzer 10 into line 104, where it
normally passes through valve 106 and line 108 to the drain line
102.
However, in the event that a temporary reversed flow of dialysis
solution is desired to assist in priming, or to remove bubbles from
dialyzer 10, both valves 98, 106 are moved to their alternate flow
positions. Accordingly, dialysis solution passing through line 92
is blocked from passage through line 94, but does pass through line
96 and valve 106 into line 104, and thus into the dialyzer in
reversed flow pattern.
The dialysis solution then exits from dialyzer 10 into line 100,
where it passes through valve 98 into drain line 102.
Referring to FIG. 3, a modification of the dialyzer and bubble trap
system of FIG. 1 is shown, which modification may be attached to
dialysis solution delivery system 14 and used in the manner
described above.
Membrane dialyzer 10a is shown, which may be similar in design to
membrane dialyzer 10 except for the design of bubble trap used.
Blood inlet conduit 24a may constitute a venous set of design
similar to the previous conduit 24. The dialysis solution inlet 28a
and outlet 30a are also used in the same manner.
Blood outlet 22a is surrounded by bubble trap 60. Bubble trap 60
comprises a hollow housing member 62, which may be in the shape of
a truncated cone having a wide end 64, which is sealed to end cap
66 of dialyzer 10a. End cap 66 may otherwise be of conventional
design.
Housing 62 also defined a narrow end 68. Blood outlet port means
70, which may be connected to conduit 72 constituting part of an
arterial set, is positioned in the wall of housing 62 as shown.
Upstanding baffle means 74 is positioned longitudinally within the
hollow housing member 62, and positioned in front of the outlet
port 70 relative to blood outlet 22a. Baffle 74 is spaced as well
from outlet port means 70, and has the function of preventing the
direct flow of blood from the outlet 22a to the outlet port means
70.
Blood filter 76 is provided as well, carried by end cap 66.
Accordingly, any bubbles which are present in the blood passing out
of port 22a are impelled upwardly, along with the general flow of
the blood, to join the gas pocket 80 at the upper part of housing
62. Outlet port 70, which is preferably positioned in the half of
the housing member wall which is adjacent to lower, wide end 64,
withdraws blood from lower portions of the blood supply in the
bubble trap 60.
A conventional needle-piercable access port 82 may be provided for
removal of gases from time to time from bubble 80 as may be
necessary. Conduit 84 communicates with the interior of bubble trap
60, and provides access for a pressure monitor device.
The above has been offered for illustrative purposes only, and is
not intended to limit the invention of this application, which is
as defined in the claims below.
* * * * *